Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Lithium-ion and lithium polymer batteries are generally composed of a lithium cobalt oxide (LiCoO2) cathode, a graphite anode, a polymer separator, and a liquid electrolyte. One drawback of these lithium-ion and lithium polymer batteries is that the liquid electrolyte presents safety issues. In some instances, the liquid electrolyte may become flammable if a short occurs between the anode and cathode of the battery (e.g., due to defects or mishandling). Another drawback of conventional lithium-ion and lithium polymer batteries is that, because these batteries have a high ratio of inactive materials (e.g., polymer separator, liquid electrolyte) to active materials (e.g., LiCoO2 cathode and graphite anode), they have a limited energy density of approximately 500-550 Wh/L.
Solid-state batteries can provide an improvement over conventional lithium-ion and lithium polymer batteries in both energy density and safety. Solid-state batteries are typically composed of a LiCoO2 cathode, a lithium anode, and a solid-state lithium phosphorous oxynitride (LiPON) electrolyte, which also acts as a separator. The lithium anode has a theoretical specific capacity of approximately 3800 mAh/g (as compared with the graphite anode used in lithium-ion and lithium polymer batteries, which has a theoretical specific capacity of only approximately 372 mAh/g), which allows for an increased energy density of solid-state batteries.
Because solid-state batteries use a solid-state electrolyte, rather than a liquid electrolyte, solid-state batteries may avoid the safety issues that lithium-ion and lithium polymer batteries do.